The spring and star washer are options for the TOP HAT case style B sensor. The top hat shape allows spring loading by use of a spring and retaining ring clip. The sensor tip is inserted into the milled hole, then the retaining ring clip is pushed down to compress the spring and retain the sensor. Using these sensors will give reliable indication as to the bearing condition. This may provide an early warning of oil film breakdown and allow the machine to shutdown and avoid unnecessary damage.